Ehhh...
There's a problem with the image labelling!!
The smaller insulators are TO-220
There's a problem with the image labelling!!
The smaller insulators are TO-220
Last edited:
Hey guys. One small question of possibly many.
I've just received the EF3-3 boards. Now I realise that a U4 or U5 case is recommended. But I have space issues. So would a U2 or U3 case be suitable? And what thermal rating should a heatsink be for this amp? Does it get hot?
More questions to follow, but will suffice for now.😆🙄
I've just received the EF3-3 boards. Now I realise that a U4 or U5 case is recommended. But I have space issues. So would a U2 or U3 case be suitable? And what thermal rating should a heatsink be for this amp? Does it get hot?
More questions to follow, but will suffice for now.😆🙄
Hi Anthony,
Please don't post in all bold.
Depending on a number of factors, only you know how hot you will run it. Smaller heat sinks limit safe power output and heat is your #1 enemy. It may also force you to use a smaller power transformer. I would reduce voltages and adapt to having a lower powered amplifier.
You could change the design and use forced air cooling in a heat tunnel. This means you need to use filters and clean/change them regularly. You may hear fan noise depending on how you design it. In any event, watch internal case temperatures nd the transformer core temperature.
Personally, I would build it as designed. Choices were made for very good reasons.
Please don't post in all bold.
Depending on a number of factors, only you know how hot you will run it. Smaller heat sinks limit safe power output and heat is your #1 enemy. It may also force you to use a smaller power transformer. I would reduce voltages and adapt to having a lower powered amplifier.
You could change the design and use forced air cooling in a heat tunnel. This means you need to use filters and clean/change them regularly. You may hear fan noise depending on how you design it. In any event, watch internal case temperatures nd the transformer core temperature.
Personally, I would build it as designed. Choices were made for very good reasons.
I have it in 3U, 400 long. With 42V AC transformer. 2x500VA and EF3-3 board. For me is ok. In winter when house is at 20C is not so hot. In summer at 35C is hot. Have lot of free room around for air circulation. But I don' use it at high volume. No partys here. It is more than enought for me. But it is crowded inside
Hi anatech.
Sorry, I wasn't aware I typed it in bold. I did it on my phone at work and it's not always apparent. I understand what you are saying. But this is Class A/B. Space where my Hi-Fi is, is at a premium. So having 4U or even 5U isn't going to fit and I'm not looking to have another monster in my room when there is already me. 🤣 There must be a workaround. I was even considering/contemplating using 4 output devices per channel instead, using a 2U case and mounting the Power Transistors vertically. It would reduce the power, but I'm OK with that.
What day think?
Cheers.... Tony
4 outputs per channel would be about 100 watts per channel, two per channel would be about 60 watts per channel.
Nice work! You've answered one question. I too was thinking about mounting the power Transistors vertically, though using a 2U case instead. and having a bank of 4 X 15000uf caps and 2X300VA. What are the other boards you have installed? Oh and being in Manchester UK, we hardly see hot temperatures and if there is, I'll be outside. 🤣
Cheers....Tony
Last edited:
Thanks RickRay.
You know, that would probably be fine. I don't have things loud these days. well, sometimes, but not enough to bring the house down LOL.
Hi Anthony,
No problem.
I would run at slightly lower voltages, reorient the heat sink. Keep the same number of output transistors.
This comes down to necessity. To get what you want it may cost more money to be creative. Fan cooling is a real consideration. You can run the fan at low speed, and use a thermal switch to kick into high speed when needed.
No problem.
I would run at slightly lower voltages, reorient the heat sink. Keep the same number of output transistors.
This comes down to necessity. To get what you want it may cost more money to be creative. Fan cooling is a real consideration. You can run the fan at low speed, and use a thermal switch to kick into high speed when needed.
Thank you anatech.
I'm going to have to cut some cardboard or even wood and trial-fit everything. I can see this turning into a nightmare. Let's see what happens and I'll post some pics as I progress with my build, which will probably be quite slow. work and family life will probably get in the way. 🙄
Cheers.....Tony
I'm going to have to cut some cardboard or even wood and trial-fit everything. I can see this turning into a nightmare. Let's see what happens and I'll post some pics as I progress with my build, which will probably be quite slow. work and family life will probably get in the way. 🙄
Cheers.....Tony
Tony:
I built an EF3-3 Wolverine for my parents a couple of years ago in a Modushop 3U chassis. Admittedly, they don't play it very loud, but that amplifier is on about 10 hours a day. Is it an ideal chassis? Perhaps not, but it's still doing its job very nicely. If you're not planning on taxing it too much (reasonable rail voltages, good air circulation, etc.) you will likely be fine.
Regards,
Scott
Attachments
After doing multiple builds, largest setup I would recommend in a 3RU chassis is a triple pair output (EF3-3) at max 57VDC rails (40VAC traffo). Wouldn't recommend the 4 pair output version on a 3RU, but I suppose you could do it if the chassis/heatsinks has enough depth. Even if I had the depth to fit the 4 pair version, I'd stick with the 3 pair version anyway. Same output power (output transistor choice dependent), less idle heat dissipation.
I've mounted my board to the heat sink. I've checked for continuity between the heat sink and the transistor legs, and they are all good [silent]. If I connect from ground to the bolt holding the transistor in place I get an alarm. I'm assuming that is because the bolt is in contact with the heat sink.
Attachments
Chiptech,
I can’t see in the pics, did you use lock or split washers between the fender washer and allen head?
With them, the heating/cooling cycles will loosen the bolt and you can guess what happens next….
I can’t see in the pics, did you use lock or split washers between the fender washer and allen head?
With them, the heating/cooling cycles will loosen the bolt and you can guess what happens next….